449 research outputs found
Homogenization of plain weave composites with imperfect microstructure: Part II--Analysis of real-world materials
A two-layer statistically equivalent periodic unit cell is offered to predict
a macroscopic response of plain weave multilayer carbon-carbon textile
composites. Falling-short in describing the most typical geometrical
imperfections of these material systems the original formulation presented in
(Zeman and \v{S}ejnoha, International Journal of Solids and Structures, 41
(2004), pp. 6549--6571) is substantially modified, now allowing for nesting and
mutual shift of individual layers of textile fabric in all three directions.
Yet, the most valuable asset of the present formulation is seen in the
possibility of reflecting the influence of negligible meso-scale porosity
through a system of oblate spheroidal voids introduced in between the two
layers of the unit cell. Numerical predictions of both the effective thermal
conductivities and elastic stiffnesses and their comparison with available
laboratory data and the results derived using the Mori-Tanaka averaging scheme
support credibility of the present approach, about as much as the reliability
of local mechanical properties found from nanoindentation tests performed
directly on the analyzed composite samples.Comment: 28 pages, 14 figure
Localization Analysis of an Energy-Based Fourth-Order Gradient Plasticity Model
The purpose of this paper is to provide analytical and numerical solutions of
the formation and evolution of the localized plastic zone in a uniaxially
loaded bar with variable cross-sectional area. An energy-based variational
approach is employed and the governing equations with appropriate physical
boundary conditions, jump conditions, and regularity conditions at evolving
elasto-plastic interface are derived for a fourth-order explicit gradient
plasticity model with linear isotropic softening. Four examples that differ by
regularity of the yield stress and stress distributions are presented. Results
for the load level, size of the plastic zone, distribution of plastic strain
and its spatial derivatives, plastic elongation, and energy balance are
constructed and compared to another, previously discussed non-variational
gradient formulation.Comment: 41 pages, 24 figures; moderate revision after the first round of
review, Appendix A re-written completel
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